Studies of Titan's atmospheric chemistry provide a unique opportunity to
explore the origin and evolution of complex organic matter in primitive
planetary atmospheres. The Atacama Large Millimeter/submillimeter Array
(ALMA) is a powerful new telescope, well suited to the study of
molecular emission from Titan's stratosphere and mesosphere. In this
talk, I will report on the first spectroscopic detection of vinyl
cyanide (C2H3CN), a molecule with potential astrobiological significance
due to its theorized ability to combine into cell membrane-like
structures under the cold conditions found in Titan's hydrocarbon lakes.
Emission maps will be presented for this gas on Titan, and compared with
the distributions of other nitriles observed with ALMA including HC3N,
CH3CN, C2H5CN and HNC. The molecular abundance patterns are interpreted
based on our understanding of Titan's high-altitude photochemistry and
time-variable global circulation. Complementary results from our more
recent (2017) nitrile mapping studies at higher spatial resolution will
also be discussed.